1. Field of the Invention
This invention relates to a method of externally actuating the “multi selector” or “multi controller” of a camera housed inside a water-proof housing and more particularly to the design of the mechanism.
2. Description of Related Art
A multi selector of a digital camera is usually in the form of a circular pad or a group of buttons which acts as a navigational tool. The multi selector allows the user to navigate the camera menu, move focus points, browse zoomed-in images while in playback mode, and also allows other functions to be performed. The multi selector usually consists of five buttons for controlling up, down, left, right directions and a button in the centre of the button arrangement, usually labeled “OK” or “SET” for confirming a selection. Some cameras may also provide diagonal movements for enhanced navigation. The multi selector is usually ergonomically located where users can reach it with their right thumb while holding the camera.
In underwater photography, a water-proof housing is used to protect the camera from water ingress as well as to allow the user to access important functions of the camera from outside the housing. The external controls of the housing are normally in the form of push buttons and levers; the linkages between these controls and the camera are usually mechanical.
Housings for digital single lens reflex (DSLR) cameras are usually large in size and rather than the user holding the body of the housing itself, the housings are often designed to be used with handles. In underwater photography, the environment changes rapidly and subjects frequently, if not usually, move very fast. Some underwater photographers prefer to change the camera settings without removing his/her eye from the viewfinder so that the users primary attention remains focused on the fast changing underwater environment. An ideal housing would have controls ergonomically located where the user can reach them without removing their hands from handles.
FIG. 1 shows a conventional method to access the multi selector from outside of the underwater camera housing. The housing has direct push buttons aligned essentially vertically in use on the housing. O-rings are provided to prevent water ingress into the housing. E-clips are provided as an aid for the positioning of the mechanism in the housing while plastic caps on the ends of the shafts are the contact points to the camera. Springs are configured so that the push buttons always return to the original position after being pressed, and when subjected under external pressure to the extent specified by the housing's depth rating.
However because of the large size of the housing the group of push buttons on the housing may not be easily reached by users without removing the hand from the handle if direct push buttons are used for accessing the multi selector which is positioned on the rear face of the housing. Also, as the group of push buttons are positioned closely packed together, it is possible that while pressing one of the buttons, others are accidentally pressed; this is especially true when pressing the centre button of the multi selector. This difficulty is increased when the user is wearing gloves.
FIG. 2 shows a modified method to address the above problem. In this construction the push buttons are re-located nearer to the edge of the housing and hence closer to the thumb. The construction uses a rigid linkage, such as flat metal bars to transfer the movement of the push buttons to the required position. FIG. 3 shows how, in this configuration, the push button is connected near to one end of the metal bar and at the end there is rod which acts as a guide for the bar; at the other end of the bar, a plastic cap is attached, which engages with the multi selector of the camera.
The principal limitation of this single metal bar connection is that due to the existence of clearance in the guiding system of the rod, the resultant vertical movement of the plastic cap, which activates the camera's button, is often less than the amount of travel of the push button. This is demonstrated in FIG. 3A and FIG. 3B which show the effect of clearance as the push button is pushed in. Furthermore, this configuration is limited to the basic four directions only, i.e. up, down, left and right but lacks control in diagonal movements.